The unique design requirement of lifting water from economically marginal gas wells, flows from a user group planning meeting on Mar. 4, 2004. PTAC (Petroleum Technology Alliance of Canada) which issued a call for technical papers on the topic of de-watering marginal shallow gas wells, with the southeast Alberta, Brooks area shallow gas pools in mind. The PTAC forum was subsequently held in Calgary, Alberta, May 12, 2004. The transcripts and reaction comments arising from the forum are available to the public. Proposals submitted for funding assistance did not meet the collective needs of the planning group at a June 2004 deadline. To date producer needs are still being met using labour intensive frequent swabbing and/or endless tubing cleanouts.
Down-hole hydraulic pumps with the valving, piston and pump (and its variations) were originally developed under the trade names “Kobe” and “Oilmaster”. Both have been available to the industry for more than five decades. The product enjoys worldwide acceptance under the current direction of Weatherford Oil Tool. These pumps find special application lifting large volumes of light oil in deep wells.
More recently Canadian application 2,258,237 by Cunningham suggested bringing the valving to the surface, and proposed using a downhole double acting hydraulic piston, three (3) strings of tube and a conventional oil well pump for placement in a horizontally drilled heavy oil well. The double acting feature of the hydraulic piston would be particularly useful as a pump pull-down in the highly viscous heavy oil applications for which the system was conceived.
Canadian application 2,260,518 proposes using a down-hole rotary hydraulic drive, coupled to a progressing cavity pump rather than the reciprocating version suggested by the Cunningham application. Both address the task of pumping heavy oil in deviated well-bores.
While not detracting from the general applicability of this invention and claim(s) therein, it is useful to focus on a specific pumping system designed for de-watering marginal gas wells.
Data has not yet been made public, quantifying the increased cash value of recoverable gas reserves expected under pumped off de-watering conditions, as cited in Canadian application 2,341,129 by Nicholson.